Physical and mechanical characterization of a porous cement for metaphyseal bone repair

Abstract

OBJECTIVE: Macroporous cement with mechanical properties similar to cancellous bone may improve the treatment of large bone defects in relation to solid acrylic cement. The aim of this study was to compare physical and mechanical characteristics of a polymethyl methacrylate (PMMA) based porous cement with cancellous bone. METHODS: Compressive strength and pore size, interconnectivity, and distribution of cylindrical porous PMMA cement samples containing 10% (G1), 20% (G2) or 30% (G3) effervescent components were analyzed. Results were compared to bovine cancellous bone (G4) and solid PMMA (G5) samples. RESULTS: Scanning electron microscopy (SEM) of all experimental samples (G1 - G3) revealed a random distribution and a wide size variation of pores ranging from 50 µm to 3 mm. Micro-CT showed that G2 have high porosity and lower interconnectivity of pores. No significant differences in yield strength and Young's modulus were observed among G1, G2 and G3. G4 samples were slightly stronger and less elastic than the other groups. Solid PMMA is extremely strong and inelastic. CONCLUSIONS: PMMA based porous cement met the expected characteristics. High porosity with large and interconnected pores may allow for bone ingrowth. Strength and elasticity similar to cancellous bone may enhance mechanical stimuli to bone remodeling. Observational Descriptive Study.

Simple method for increasing drug elution from polymethylmethacrylate bone cement

“…They also showed that the strength of aforementioned cement was comparable with cancellous bone. [5] In this study, we demonstrated the efficacy of this novel porosity inducing method for better drug elution. We explained the elution of drugs through PMMA spacers by using porosity, permeability, and dissolution rate principles and criticized the literature for neglecting and not reporting on such important data in relevant studies.…”

“…Cimatti et al [5] proposed a method for creating "interconnected macro-pores" inside the cement. They proposed that this type of cement may be used to fill irregularly shaped bone defects by expansion and those macro-pores may act as a scaffold for tissue ingrowth.…”

“…In our experiment, we first experimented with the method proposed by Cimatti et al [5] and noted that the final products porosity may be greater than required for this purpose. Thus, we decided to reduce the amount of effervescent and created E 2 P 1 batch for the test.…”

“…Therefore, we believe that our samples' mechanical properties were also better than their samples, which were measured and were close to bovine bone. [5] It is not known how much compressive strength a knee spacer must have. Although we did not measure this, it was hard to break our sample even with a large chisel or hammer.…”

“…Cimatti and Engel described such a method for increasing the porosity of PMMA cement. [5] They proposed to use citric acid and sodium bicarbonate mixture as an effervescent in PMMA cement. Therefore, in this study, we aimed to investigate the effects of the use of citric acid and sodium bicarbonate mixture as an effervescent in PMMA bone cement in terms of better drug elution.…”